What's the point of maintaining personal fork of browser? Are you adding some feature to it, or auditing every commit since last release for security/privacy pu

What's the point of maintaining personal fork of browser? Are you adding some feature to it, or auditing every commit since last release for security/privacy purpose? If former, I doubt you can switch from Chrome to Firefox as easily as the way you chosen the words. If latter, I doubt any person in this planet have the expertise or bandwidth to do so due the complexity and size of the code base, not to mention you already be annoying by just building it.